U.S. patent number 4,597,567 [Application Number 06/665,319] was granted by the patent office on 1986-07-01 for adjustable torsion spring.
This patent grant is currently assigned to Barry Wright Corporation. Invention is credited to Romulus Racca.
United States Patent |
4,597,567 |
Racca |
July 1, 1986 |
Adjustable torsion spring
Abstract
A spring for creating adjustable torsional resistance between
two members which are pivotal relative to each other. The spring
comprises a stack of axially aligned elastomer torsion rings (30).
A locking ring (34) is secured to and separates adjacent torsion
rings, one locking ring being associated with each torsion ring.
The assembled stack is firmly attached to one of the pivotal
members (14). There is connecting sleeve (46) engageable
selectively with each locking ring and with the other relatively
pivotal member. The number of torsion rings exposed to pivotal
motion between the members to vary the torsional resistance of the
spring is determined by engagement between the connecting sleeve
and selected locking rings.
Inventors: |
Racca; Romulus (Weston,
MA) |
Assignee: |
Barry Wright Corporation
(Newton, MA)
|
Family
ID: |
24669622 |
Appl.
No.: |
06/665,319 |
Filed: |
October 26, 1984 |
Current U.S.
Class: |
267/140.2;
248/397; 248/575; 248/609; 267/141.1; 267/153; 267/154; 297/302.5;
297/302.3; 297/303.3 |
Current CPC
Class: |
F16F
1/40 (20130101); F16F 1/3615 (20130101); A47C
3/025 (20130101); F16F 2236/08 (20130101); F16F
2236/106 (20130101) |
Current International
Class: |
A47C
3/025 (20060101); A47C 3/02 (20060101); F16F
1/40 (20060101); F16F 1/36 (20060101); F16F
001/14 (); F16F 001/36 () |
Field of
Search: |
;267/154-157,153,140.2,140.4,141,141.1-141.7,57.1R,57,63,54A,57.1A,131,133
;297/301,303,304,333 ;248/609,608,561,397,575,576
;16/308,298-301,DIG.36 ;403/132,133 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Butler; Douglas C.
Attorney, Agent or Firm: Gilbert; Milton E. Ross; Gary
E.
Claims
I claim:
1. A spring for creating adjustable torsional resistance between
two members which are pivotal relative to each other,
comprising:
a stack of axially aligned elastomer torsion rings, each torsion
ring having an internal aperture,
axially aligned locking rings firmly secured to and separating
adjacent torsion rings, there being one locking ring associated
with each torsion ring, each locking ring having an internal
aperture,
the stack of torsion rings and locking rings being firmly attached
to a first pivotal member,
an elongate connecting means slidable into and out of the aperture
in the stack,
at least one axially extending slot in the connecting means,
at least one tang on each locking ring projecting into the aperture
in the stack and aligned with and engageable within the slot in the
connecting means,
means preventing the connecting means from rotating relative to the
second pivotal member and
means for positioning the connecting means at predetermined axial
positions relative to the stack to engage the slot in the
connecting means selectively with the tangs of one or more locking
rings to selectively change the number of torsion rings exposed to
the pivotal motion between the members to vary the torsional
resistance of the spring.
2. A spring according to claim 1
wherein one of the two members which are pivotal relative to each
other is stationary.
3. A spring according to claim 1
wherein the connecting means is a slotted sleeve.
4. A spring according to claim 1
wherein there are adjustable means for limiting the degree of
pivotal movement between the two relatively pivotal members.
5. A spring for creating adjustable torsional resistance between
two members which are pivotal relative to each other,
comprising:
a stack of axially aligned elastomer torsion rings, each torsion
ring having an internal aperture,
axially aligned locking rings firmly secured to and separating
adjacent torsion rings, there being one locking ring associated
with each torsion ring,
one end of the stack of torsion rings and locking rings being
firmly attached to a first relative pivotal member,
a connecting sleeve slidable into and out of the aperture in the
stack,
at least one axially extending slot in the connecting sleeve,
at least one tang on each locking ring projecting into the aperture
in the stack and aligned with and engageable within the slot in the
sleeve,
means preventing the sleeve from rotating relative to the second
relative pivotal member and
means for positioning the sleeve at predetermined axial positions
relative to the stack to engage the slot in the sleeve selectively
with the tangs of one or more locking rings to selectively change
the number of torsion rings exposed to the pivotal motion between
the members to vary the torsional resistance of the spring.
6. A spring according to claim 5
wherein the means for preventing the sleeve from rotating is a rod
attached to the second relative pivotal member and upon which the
sleeve is slidable, the sleeve being keyed to the rod.
7. A spring according to claim 5
wherein the second relative pivotal member is attached to a rod
upon which the sleeve is slidable,
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod,
the spacing between the holes being the same as the spacing between
the locking rings, each locking ring being associated with one
hole.
8. A spring according to claim 5
wherein the second relative pivotal member is attached to a rod
upon which the sleeve is slidable,
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod to engage selected
locking rings,
the spacing between the holes being the same as the spacing between
the locking rings, each locking ring being associated with one
hole,
there being one more hole in the rod than there are locking rings,
which hole is not associated with any locking ring,
whereby when the detent is in the non-associated hole, none of the
torsion rings are exposed to pivotal motion and the pivotal member
is free to pivot on the rod.
9. A spring according to claim 5
wherein the second relative pivotal member is attached to a rod
upon which the sleeve is slidable,
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod to engage selected
locking rings,
the spacing between the holes being the same as the spacing between
the locking rings, each locking ring being associated with one
hole,
one of the locking rings being firmly secured to the first relative
pivotal member
whereby when the detent is in the hole associated with the secured
locking ring the first relative pivotal member is locked to the rod
to prevent the members from pivoting relative to each other.
10. A spring for creating adjustable torsional resistance between a
fixed member and pivotal member comprising:
a stack of axially aligned elastomer torsion rings, each torsion
ring having an internal aperture,
axially aligned locking rings firmly secured to and separating
adjacent torsion rings, there being one locking ring associated
with each torsion ring, each locking ring having an internal
aperture,
one end of the stack of torsion rings and locking rings being
firmly secured to the pivotal member,
a rod passing through the internal aperture in the stack of aligned
torsion rings and locking rings, the rod being firmly secured to
the fixed member,
a connecting sleeve slidable on the rod into and out of the
aperture in the stack,
at least one axially extending slot in the connecting sleeve,
and
at least one tang on each locking ring projecting into the aperture
in the stack and aligned with and engageable within the slot in the
connecting sleeve and
means for positioning the sleeve at pre-determined positions on the
rod to engage the slot in the sleeve selectively with the tangs of
one or more locking rings to selectively change the number of
torsion rings exposed to the pivotal motion between the members to
vary the torsional resistance of the spring.
11. A spring according to claim 10
wherein the positioning means includes:
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod to engage the tangs of
selected torsion rings.
12. A spring according to claim 10
wherein the positioning means includes:
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod,
the spacing between the holes being the same as the spacing between
the locking rings, each locking ring being associated with one
hole.
13. A spring according to claim 10
wherein the positioning means includes:
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod to engage the tangs of
selected locking rings,
the spacing between the holes being the same as the spacing between
the locking rings, each locking ring being associated with one
hole,
there being one more hole in the rod than there are locking rings,
which hole is not associated with any locking ring,
whereby when the detent is in the non-associated hole none of the
torsion rings are exposed to pivotal motion and the pivotal member
is free to pivot on the rod.
14. A spring according to claim 10 wherein the positioning means
includes:
spaced holes in the rod and
detent means on the sleeve engageable selectively with each hole to
position the sleeve lengthwise on the rod to engage selected
locking rings,
the spacing between the holes being the same as the spacing between
the locking rings, each locking ring being associated with one
hole,
one of the locking rings being firmly secured to the pivotal
member
whereby when the detent is in the hole associated with the secured
locking ring the pivotal member is locked to the rod to prevent
pivoting.
Description
TECHNICAL FIELD
This invention relates in general to springs for creating
adjustable torsional resistance between two members which pivot
relative to each other and more specifically to adjustable torsion
springs which have particular utility in seats, chairs and the
like.
BACKGROUND OF THE INVENTION
Generally, seats, chairs, rockers and for that matter any device
intended to pivot or rock relative to a base, conventionally uses
metal coil springs to create torsional resistance to the rocking
motion. To increase or decrease the degree of stiffness of the
spring, mechanisms are usually employed to change the torsional
properties of the spring by twisting or compressing the spring or
otherwise changing its shape.
While the desired results of torsional adjustability usually have
been obtained, it has not been without ancillary problems. Friction
occurs between the spring and the adjusting mechanism (usually
metal) used to compress or twist it. Lubrication is required, not
only to reduce friction, but also to prevent squeaking. The
mechanisms are frequently complex and often costly to
manufacture.
Another problem with springs which require their shape to be
changed to vary their torsional properties is that considerable
force is necessary to deform the spring. Hand wheels, levers, and
cams used for this purpose require considerable manual strength to
operate, often more than can be summoned, if the user is of
advanced age or is infirm.
Accordingly, one of the objects of this invention is to produce an
adjustable torsion spring, the torsional properties of which may be
varied with little human effort being required.
Another object of the invention is to produce an adjustable torsion
spring which is relatively frictionless and requires little or no
lubrication.
Yet another object is to produce a simple, inexpensive adjustable
spring, the torsional properties of which may be changed without
changing the shape of the spring.
SUMMARY OF THE INVENTION
In accordance with the above objects, the invention resides in a
spring for creating adjustable torsional resistance between two
members which are pivotal relative to each other. The spring
comprises a stack of axially aligned elastomer torsion rings,
separated by axially aligned locking rings which are firmly secured
to the elastomer rings by vulcanization or the like. Connecting
means are provided which are engageable selectively with each
locking ring and with one of the pivotal members while the stack of
torsion rings is firmly attached to the other pivotal member. The
amount of torsional resistance is the inverse function of the axial
length of the spring. The location of the connecting member
determines the number of torsion rings which are exposed to the
rocking motion between the pivotal members. This determines its
effective length of the spring and hence its stiffness.
The above and other features of the invention including various
novel details of construction and combinations of parts will now be
particularly described with reference to the accompanying drawings
and pointed out in the claims. It will be understood that the
particular adjustable torsion spring embodying the invention is
shown by way of illustration only and not as a limitation of the
invention. The principles and features of this invention may be
employed in varied and numerous embodiments without departing from
the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation, including a human figure, of a chair
having torsin spring mechanism embodying the features of the
present invention.
FIG. 2 is a front view of the chair shown in FIG. 1 but with the
figure removed.
FIG. 3 is a perspective view with parts broken away of the chair
shown in FIG. 1 on which a pair of adjustable torsion springs are
employed.
FIGS. 4 and 5 are sectional views of the adjustable torsion spring
shown in two positions of adjustment.
FIG. 6 is an end view of a locking ring taken in the direction of
the arrow VI on FIG. 4.
FIG. 7 is a sectional view through the torsion spring taken in the
direction of the arrows VII--VII on FIG. 4.
FIG. 8 is a spring biased detent which may be employed as an
alternative element in the spring.
BEST MODE OF CARRYING OUT THE INVENTION
The invention as seen in FIGS. 1 to 3 is employed with a seat 2
which is mounted for limited pivotal or rocking motion on a base 4.
The seat and base are representative of a platform rocker, a
wheelchair, an office chair or any other form of chair. As will
become apparent hereinafter, the invention may in its broadest
sense be embodied in any mechanism requiring a spring for creating
adjustable torsional resistance between two members which pivot
relative to each other.
The seat 2 pivots about an axis A which extends horizontally
between two support members 6 and 8 extending upwardly from the
base 4. The axis A is defined by the center of a bar or rod 10
which extends between the support members 6 and 8. Its ends are
secured against rotation as, for example, by being keyed to flanges
12 in the support members (one of which is seen in FIG. 3).
The seat 2 has a pair of depending brackets 14 and 16 pivotally
mounted on the bar 10 as will be described in more detail
hereinafter. The degree of angular pivoting of the seat 2 relative
to the base 4 is limited by stops 18 threaded for vertical
adjustment in portions 20 of the supports 6 and 8. Depending
bumpers 22, two each on the front and back of the seat 2, engage
the forward and rearward stops 18 to limit the amount of forward
and rearward tilting motion.
One of the two identical adjustable torsion springs S shown in the
illustrated embodiment of FIGS. 1-3 will now be described with
particular reference to FIGS. 4-7. Each torsion spring S comprises
a stack of axially aligned elastomer torsion rings or segments 30a,
30b and 30c which are circular disks having holes 32 in their
centers. The elastomer disks are separated by locking rings in the
form of circular plates 34a, 34b, 34c and 34d of the same diameter
as the torsion rings and each having a hole 36 in the center of the
same diameter as the holes 32 in the torsion rings.
As will be seen in FIG. 6, the locking ring or plate 34d (as well
as the other rings) has at least one and preferably two
diametrically opposed tangs 42 and 44 extending into the hole 36.
The torsion rings and locking rings are firmly bonded together by
vulcanizing or other elastomer-to-metal bonding means. The endmost
locking plate 34a is securely fastened by a weldment 35 or the
equivalent to the face of the bracket 14 which depends from the
seat 2. The rod 10 passes through the centers of the assembled
elastomer rings and locking plates. It also passes through a
bearing 45 in the depending bracket 14 permitting the bracket and
hence the seat 2 to pivot on the non-rotatable bar 10.
Connecting means in the form of a circular sleeve 46 is slidably
mounted on the bar 10 and is movable into and out of the aligned
holes 32 in the elastomer disks 30 and the holes 36 in the locking
plates 34. The outer diameter of the sleeve 46 is slightly less
than the diameter of the holes 32, 36 in the torsion disks and
locking plates to permit easy sliding motion therebetween.
Conversely, the inner diameter 48 of the sleeve 46 (see FIG. 7) is
slightly larger than the outer diameter of the bar 10, also to
permit easy sliding motion.
A slot 50 is formed in the outer diameter of the sleeve 46 to
engage the tangs 42 of the locking rings 34. In alignment with the
slot 50 is a diametrically opposite slot 52 to engage the tangs 44
of the locking rings 34. The tangs 42 and 44 (see FIG. 6) extending
into the holes in the centers of the locking plates 34 are
receivable within the slots 50 and 52 respectively as will be
explained in more detail hereinafter.
While capable of sliding motion axially of the rod 10, the sleeve
46 is prevented from rotating around the rod by a sunk key 56 which
fits in a slot 58 in the sleeve 46 and a mating slot 59 in the rod
10. The slot 59 in the rod 10 is longer than the sleeve 46 to
permit sliding movement of the sleeve relative to the rod.
A plurality of holes 60a to 60e are formed in the rod 10
diametrically opposite the slot 59. A detent in the form of a thumb
screw 62 is threaded into a tapped hole 64 at the right hand end of
the sleeve 46 as seen in FIGS. 4 and 5. A detent portion 66 of the
screw 62 is engageable selectively in holes 60a through 60e in the
rod 10 to lock the sleeve at selective positions on the rod 10 and
hence relative to the spring S.
The center line spacing between adjacent holes 60 is equal to the
centerline spacing of the locking plates 34. It will be noted,
however, that there is one more hole than there are locking
plates.
The adjustable torsion spring operates as follows: As viewed in
FIG. 4, the thumb screw 62 is positioned in the hole 60d in the rod
10. As a result, the walls of the slots 50 and 52 in the sleeve 46
engage the tangs 42-44 of only the locking plate 34d. This exposed
all three elastomer segments 30 a, b and c to rocking motion of the
seat, which motion is transmitted through the depending brackets 14
and the locking plate 34a which is firmly secured to it. This
particular setting with all three elastomeric segments exposed to
torsional stress (the sleeve 46 and the rod 10 being locked against
pivotal motion) results in the least amount of torsional rigidity
of the spring. This is because torsional resistance is an inverse
function of the length of the spring or of the number of elastomer
segments exposed to twisting.
When greater stiffness is required, the thumb screw 62 is removed
from the hole 60d and the sleeve is moved to the left as, for
example, to the FIG. 5 position and inserted into the hole 60b. The
walls of the slots 50-52 in the sleeve engage the tangs on locking
plates 34b, c and d. This also locks out elastomer disks 30b and
30c permitting only disk 30a to offer resistance to the rocking
motion of the chair. This results in the maximum spring
stiffness.
Should it be desired to completely immobilize the spring and lock
the seat against all rocking, the sleeve 34 is moved as far to the
left as possible and the thumb screw 62 is inserted into the hole
60a. At this time the walls of the slots 50 and 52 engage the tangs
42 and 44 of all of the locking plates including the endmost plate
34a which is fixed to the bracket 14. This prevents motion from
being transmitted to any of the elastomer disk segments and thus
locks the seat in non-rocking position.
As an alternative to the wing nut 62, a spring biased detent 70
seen in FIG. 8 may be threaded in the sleeve 46. Its detent tip 71
is removed from engagement with any hole 60 merely by pulling up on
the upper ball portion 72 and when the tip 71 is in alignment with
a desired hole is allowed to drop into it under the force of
compression spring 74. This construction aids persons of little
manual dexterity.
As the degree of stiffness of the spring S is adjusted simply by
sliding the sleeve 46 in and out of the spring successively to
engage the desired locking disks, the amount of forward and
backward movement can also be adjusted by screwing the threaded
stops 18 upwardly or downwardly in bracket portions 20 on the base
4 of the chair. To make this procedure easier, sleeve 46 would be
moved as far to the right as possible, placing the thumb screw 62
or detent 70 in hole 60e. This completely disengages the sleeve 46
from contact with all locking disks, permitting the seat to pivot
freely on the rod 10.
It will thus be seen that the tension of the spring may be adjusted
without changing its shape, its tension being determined by the
positioning of the locking sleeve. By this mechanism, people with
little manual strength may adjust their chair, be they wheelchairs,
platform rockers, hospital chairs and the like with little or no
assistance from others.
While two springs are shown in the illustrative embodiment located
inboard of the depending brackets 14 and 16, they could, without
departing from the scope of the invention, be located outboard
thereof or even outboard of the brackets 6 and 8 (with the brackets
14 and 16 and brackets 6 and 8 reversed) to make the springs more
accessible to the user. A single spring may be employed as long as
one end is firmly connected to the seat and the other keyed to the
rod. In its broadest sense, the adjustable torsion spring would not
be limited to use with a seat but could be used with any two
members which pivot relative to each other.
* * * * *